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Physical Properties

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Magnesium is used in both its pure form and as an alloy. Depending on the composition of the metal, there can be notable differences in many physical properties. The data below is primarily regarding pure magnesium however several common alloys are also included in the data and will be noted accordingly.

About the Element Magnesium

Silvery, white metal

Symbolized by Mg on periodic table

Atomic #12

Atomic weight of 24.305

Atomic radius of 0.160 nm (6.3x10-9in)

Part of the s-block and group 2A (alkaline earth metals)

Has two valance electrons

Has 3 natural isotopes with mass numbers 24,25 and 26

Has a hexagonal close packed (HCP) crystal structure in pure form

Standard state is solid at a temperature of 298K

At a density of 1.7g/cm3(106.13lb/ft3) at 20°C (68°F), it is the least dense of structural metals

Thermal Properties

Boiling Point: 1107±10°C (2024.6±50°F)

Enthalpy:

T (°C)

T (°F)

Enthalpy (kJ/kg)

Enthalpy (BTU/lb)

127

260.6

107

46.0

227

440.6

218

93.7

427

800.6

454

195.2

627

1160.6

709

304.8

727

1340.6

1202

516.8

1127

2060.6

7287

3132.8

1727

3140.6

7800

3353.4

2727

4940.6

8656

3721.4

Entropy:

T (°C)

T (°F)

Entropy (kJ/kg•K)

Entropy (BTU/lb•F°)

20

68

1.34

.320

127

260.6

1.65

.394

327

620.6

2.11

.504

527

980.6

2.46

.588

727

1340.6

3.15

.752

927

1700.6

3.41

.814

1027

1880.6

3.52

.840

1127

2060.6

7.62

1.82

1727

3140.6

7.93

1.89

2727

4940.6

8.27

1.98

Heat of Combustion: 25.1 MJ/kg (10,791.06 BTU/lb)

Heat of Fusion: The specific heat of fusion if only slightly affected by alloying meaning that the values for alloys and pure magnesium are close. The heat of fusion for pure magnesium is 0.370± 0.015 MJ/kg (159.07±±6.45 BTU/lb).

Heat of Vaporization:

T (°C)

T (°F)

Heat of Vaporization

Boiling Point

Boiling Point

5.26-5.65

438

820.4

5.69

829

1524.2

5.51

MeltingPoint/Range:

Alloy

T (°C)

T (°F)

Pure Magnesium

650

1202

AZ91D

470-595

875-1105

AZ81

490-610

915-1130

AM20

618-643

1145-1190

AM50A

543-620

1010-1150

AM60B

540-615

1005-1140

AE42

565-620

1050-1150

AE42

565-620

1050-1150

Specific Heat:

T (°C)

T (°F)

Specific Heat (kJ/kg•K)

Specific Heat (BTU/lb•°F)

-253

-423.4

.015

.004

27

80.6

.914

.218

127

260.6

1.026-1.084

.245-.259

327

620.6

1.178

.281

527

980.6

1.277-1.278

.305

649 (solid)

1200.2 (solid)

1.361

.325

650 (liquid)

1202 (liquid)

1.323

.316

727

1340.6

1.357-1.358

.324

827

1520.6

1.402-1.403

.335

1127-2727 (gas)

2060.6-4940.6 (gas)

8.563

2.045

Thermal Conductivity: The thermal conductivity of magnesium is slightly affected by temperature variations. Alloying has a great effect on thermal conductivity. The thermal conductivity values are calculated from electrical conductivity values.

Pure Magnesium:

T (°C)

T (°F)

Thermal Conductivity (W/m•K)

Thermal Conductivity (BTU/hr•ft•°F)

-173

-279.4

169

97.65

0

32

157

90.71

20

68

147-168

84.94-97.07

25

77

156

90.14

50

122

149

86.09

100

212

148

85.51

200

392

146-163

84.36-94.18

300

572

145

83.78

400

752

130-143

75.11-82.62

Linear Thermal Expansion Coefficient: Alloying only has a minimal effect on the coefficient value.

T (°C)

T (°F)

Specific Heat (kJ/kg•K)

0-160

32-320

27.3

20-100

68-212

26.0-26.1

20-200

68-392

27.0-27.1

20-300

68-572

27-28

20-400

68-752

28.9

20-500

68-932

29

Solidification Shrinkage: The amount of shrinkage that occurs when pure magnesium goes from liquid to solid, relative to the volume of the liquid metal, is 2.96-4.20 percent liquid volume.

Electrical Properties

Electrical Conductivity:

Alloy

Conductivity at 20°C (68°F) (MS/m)

AZ31

10

18.5% IACS

AZ61

8.28

11.6% IACS

AZ63

15% IACS

AZ81

7.3

12% IACS

AZ91

7.1

10.1% IACS

AZ8

7.5

AZ41

9.7

Electrical Resistivity:

Alloys at 100°C (212°F)

Electrical Resistivity (nΩ•m)

Electrical Resistivity (nΩ•in)

AM20

89

3503.9

AE42

98

3858.3

AS21

104

4094.5

AM50

122

4803.1

AZ91

163

6417.3

Pure Magnesium

60

2362.0

Pure Magnesium at Varying Temperatures:

T (°C)

T (°F)

Electrical Resistivity (nΩ•m)

SElectrical Resistivity (nΩ•in)

20

68

44-45

1732.3-1771.7

50

122

50.1

1972.4

100 (Extruded)

212 (Extruded)

58.5

2303.1

100

212

56

2204.7

300 (Extruded)

572 (Extruded)

93

3661.4

300

572

95

3740.2

400 (Extruded)

752 (Extruded)

121

4763.8

600

1112

170

6692.9

649 (solid)

1200.2 (solid)

154

606

650-900 (liquid)

1202-1652 (liquid)

274-288

10787-11339

Other Properties

Surface Tension: In pure magnesium, it is linear inside the temperature range of 681-894°C (1257.8-1641.2°F). When the elements Li, Ca, Sb, Sr, Pb, Ba, or Bi are added, surface tension is reduced. For solid magnesium, surface tension close to -273°C (-459.4°F) is 1.447N/m (.099lb/ft) and at 25°C (77°F) it is 0.190N/m (.013lb/ft).